#include <stdio.h>
bool prime[1000001];
int a[1000001],phi[1000001];
int main()
{
    FILE *fin,*fout;
    fin=fopen("fractii.in","r");
    fout=fopen("fractii.out","w");
    int n;
    long long int s=0;
    fscanf(fin,"%d",&n);
    for(int i=1;i<=n;i++) phi[i]=i-1;
    for(int i=2;i<=n;i++)
    {
        for(int j=2*i;j<=n;j+=i) phi[j]-=phi[i];
        s+=phi[i];
    }
    fprintf(fout,"%lld",2*s+1);
}